<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<script>
    function add(a, b){
        return a + b;
    }

    var result = add(1, 3);

    alert(result);



    var add = function(b, c){
        return b + c;
    }

    let result1 = add(4, 6, 8);
    alert(result1);

    var result2 = add(1);
    alert(result2);

</script>

</body>
</html>